This invention relates to a sealing assembly for sealing a connector cavity and in particular for sealing an electric circuit of a connector. More precisely, the present invention relates to a sealing assembly including a sealing core having inserting holes and an outer inserting layer adapted to protect a lip profile of the inserting holes. Further, the present invention relates to a connector including the sealing assembly of the present invention.
Known prior art arrangements for sealing multiple contacts connectors consist of a substrate made of silicon material including several openings or insertion holes through which female or male contacts can be inserted so as to reach the corresponding mating contacts in the connector. The silicon material used for the sealing arrangement is elastic so that the insertion holes can be stretched upon insertion of the contact to allow the contact passing through the sealing arrangement. Once the contact is fully inserted in the connector, the insertion hole in the silicon sealing arrangement recovers its original shape and seals the cable contact so that no liquid or dirt penetrates the connector.
Such multiple seal arrangements are known in the art as “Grommet seals” and are preferred to single wire seals because their use simplifies the wiring process, since single wire seals do not have to be assembled directly on each wire. Moreover, using multiple seals allows reducing the dimensions of the connector, since the design does not require individual channels for housing each contact and the associated wire seal. However, the sealing performances of common Grommet seals are influenced by the design of the contact and the profile of the insertion hole of the seal. The profile of the insertion hole will be indicated in the following also as lip profile. Further, contact insertion and withdrawal from the cavity can cause damages to the profile of the insertion opening forming tears or cuts extending from the inserting hole into the sealing arrangement.
In the connector industry, contacts are classified in female and male contacts. Male contacts may be a tab (rectangular-shaped) or pin (square-shaped with surface equal or smaller than 1 mm2). Female contacts used for automotive applications may have a rectangular shape or a square shape and in some cases a round shape. Therefore, during contact insertion into the inserting hole, which is typically circular and has a smaller section than the contact and the cable to be sealed, the insertion force of the contact is concentrated on the portions of the lip profile contacting the vertices of the contact housing. Consequently, these portions of the lip profile are exposed to high elongation and stresses, which cause tears or cuts. In addition, if the contact is stamped, the edges of the contact may have burrs which can damage portions of the grommet seal that comes into contact with the contact pin. Cuts in the profile of the insertion opening prejudice the sealing performance of the multiple seal.
A connector cavity 600 including a Grommet seal 610 according to the prior art is shown in FIG. 6. In this figure, the contacts 300 are in their final position and are sealed by the Grommet seal 610.
FIG. 7 shows a circular insertion hole 720 of a Grommet seal 610 according to the prior art. In particular, the Grommet seal 610 includes an entry region 710 made of a tin elastic layer of silicon or rubber. The insertion hole 720 is located at the center of the entry region 710.
FIG. 8 shows an insertion process of a female contact 300 into the Grommet seal 610. In particular, the elastic layer of rubber of silicon of the entry region 710 is stretched during insertion of the female contact 300. Once the contact 300 has been completely passed through the insertion hole, the entry region 710 will recover its original shape so as to be tight around the contact cable.
FIG. 9 shows a top view of a Grommet seal 610 according to the prior art. The tears or cuts 650 that extend from the border of the insertion holes 720 along the surface of the Grommet seal 620 are ruptures of the seal due to the high stresses caused by reiterated insertions and withdrawals of contacts into the connector cavity.
In order to increase the lifetime of a Grommet seal and its sealing properties, several solutions are known in the art. As an example, Grommet seals, such as those described with reference to FIGS. 7 to 9 may be lubricated so as to facilitate a smooth insertion of the contacts. However, this solution can not avoid concentrating high stresses on specific portions of the lip profile during insertion of a contact. Therefore, while using lubricated materials might help protect the entry region of a Grommet seal 600 from cuts caused by the rough surface of a contact, this solution cannot avoid structural damages caused by overstretching the Grommet seal around the entry region during insertion of a contact.
Alternatively, other solutions known in the art for sealing connector cavities involve the use of greases or gel materials. These materials are capable of withstanding high stresses, since they lack a structural network. However, despite the fact that the sealing performances of gel sealants were found to be very good, this solution has several shortcomings. More precisely, due to the lack structural network, the sealant results to be generally viscous and changes its structure when subjected to temperature changes, thereby providing an unstable means for protecting the contacts or wires. Further, when a contact is passed through the gel, portions of the gel sealant contacting the edges of the contact are exposed to a high pressure and the contact takes away some particles of the gel. This makes the wiring surface of the contact dirty after few insertions and withdrawals during the testing process of the connector. Moreover, the presence of non-conductive particles on the contacts causes a deterioration of the conduction properties of the contacts, thereby compromising the correct functioning of the connector.